Technical Field
Embodiments of this invention relate to a sheet conveying device and an image forming apparatus employing the sheet conveying device.
Related Art
Hitherto, in image forming apparatuses such as printers, copiers, etc., since the sheet is sometimes skewed when conveyed from a sheet feeding unit, a known system corrects this skew of the sheet.
For example, a gate (i.e., a sheet skew corrector for correcting a skew of the sheet) is placed downstream of a pair of registration rollers in a sheet conveyance direction to open and close a paper sheet conveyance path for the paper sheet. When the paper sheet conveyance path is closed by the gate while the pair of registration rollers is separated from each other, the pair of conveyance rollers placed upstream of the pair of registration rollers in the paper sheet conveyance direction is driven to bring a leading end of the paper sheet in contact with the gate. Since the paper sheet is further conveyed for a predetermined period of time even after being brought into contact with the gate, the leading end of the paper sheet abuts against and is aligned with an abutment face of the gate, thereby making a right angle with the paper sheet conveyance direction. Subsequently, the pair of registration rollers contacts each other to sandwich the paper sheet to regulate movement of a leading end region of the paper sheet while keeping the leading end of the paper sheet contacting the gate. As a result, the skew of the paper sheet caused in the leading end region of the paper sheet between a portion thereof sandwiched by the pair of registration rollers and the leading end thereof is corrected.
At this moment, since a trailing end region of the paper sheet located upstream of the portion sandwiched by the pair of registration rollers is sometimes obliquely sandwiched by the pairs of conveyance rollers, the trailing end region of the paper sheet inclines to the leading end of the paper sheet thereby generating torsion in the paper sheet. In such a torsional condition, however, when the gate is opened the pair of conveyance rollers is at the same time separated, so that the trailing end of the paper sheet can make the right angle with the paper sheet conveyance direction as the portion sandwiched by the pair of registration rollers. Hence, the torsion of the paper sheet is thereby wholly eliminated therefrom. Thus, when the pair of registration rollers is driven at a prescribed time after that, the paper sheet is sent to a transfer section with the skew corrected.